Microstructural evolution in Al-Mn-Cu-(Be) alloys

Niko Rozman (1) , Jozef Medved (2) , Franc Zupanic (1)

1 FME - Faculty of Mechanical Engineering [Maribor]
2 Faculty of Natural Sciences and Engineering [Ljubljana]

This article investigates the effects of alloying elements on the microstructural evolution of Al-rich Al-Mn-Cu-(Be) alloys during solidification, and subsequent heating and annealing. The samples were characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy, synchrotron X-ray diffraction, time-of-flight secondary-ion mass spectroscopy, and differential scanning calorymetry. In the ternary Al94Mn3Cu3 (at. %) alloy, the phases formed during slower cooling (≈ 1 K s−1) can be predicted by the known Al-Mn-Cu phase diagram. The addition of Be prevents the formation of Al6Mn, decreases the fraction of tau1-Al29Mn6Cu4, and increases the fraction of Al4Mn. During faster cooling (≈ 1000 K s−1), Al4Mn predominantly forms in the ternary alloy, whereas in the quaternary alloys the icosahedral quasicrystalline phase dominates. Further heating and annealing of the alloys causes an increase in the volume fractions of tau1 in all alloys, and Be4Al(Mn,Cu) in quaternary alloys, while fractions of all other intermetallic phases decrease. Solidification with a moderate cooling rate (≈1000 K s−1) caused considerable strengthening, which was reduced by annealing for up to 25 % in the quaternary alloys, while hardness remained almost the same in the ternary alloy.

Mots clés: Physical Sciences

Domaines: Matière Condensée [cond-mat]

Niko Rozman, Jozef Medved, Franc Zupanic. Microstructural evolution in Al-Mn-Cu-(Be) alloys. Philosophical Magazine, 2011, pp.1. ⟨10.1080/14786435.2011.608733⟩. ⟨hal-00728899⟩